# \[PATCH net-next v20 12/13\] ax88179\_178a: Add support for AX88179A/772D/279 EEPROM access

- From: Birger Koblitz \<hidden\>
- Date: 2026-11-06 07:21:44 
- List: netdev
- Page: https://ratatoskr.run/netdev/2026/11/17876240
- Thread: https://ratatoskr.run/linux-usb/2026/11/17876248/t.md

```text
The AX88179A/772D devices have 32 efuses with 20 bytes each,
which can be randomly programmed. The AX88279 has 16K FLASH.

Provide ethtool read capability for these devices. However,
no write access is provided.

Signed-off-by: Birger Koblitz <redacted>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
---
 drivers/net/usb/ax88179_lib.c | 56 +++++++++++++++++++++++++++++++++----------
 1 file changed, 43 insertions(+), 13 deletions(-)

diff --git a/drivers/net/usb/ax88179_lib.c b/drivers/net/usb/ax88179_lib.c
index b54e98e781f334c5aeff0b3d2861a5565934454c..d5bbaa0c4e4c6f978722a6ec4461bb1d45679e15 100644
--- a/drivers/net/usb/ax88179_lib.c
+++ b/drivers/net/usb/ax88179_lib.c
@@ -210,36 +210,61 @@ int ax88179_set_wol(struct net_device *net, struct ethtool_wolinfo *wolinfo)
 	return 0;
 }
 
+static void
+ax88179_eeprom_access_params(struct ax88179_data *ax179_data, int i, u16 *value, u16 *idx)
+{
+	/* AX88179 has a word-addressable EEPROM
+	 * AX88179A uses EFUSES with 20 bytes length
+	 * AX88279 has an EEPROM addressable in 256 byte blocks
+	 */
+	if (ax179_data->chip_version < AX_VERSION_AX88179A) {
+		*value = i;
+		*idx = 1;
+	} else if (ax179_data->chip_version == AX_VERSION_AX88279) {
+		*value = (i * ax179_data->eeprom_block) >> 16;
+		*idx = (i * ax179_data->eeprom_block) & 0xffff;
+	} else {
+		*value = i << 4;
+		*idx = 0;
+	}
+}
+
 int ax88179_get_eeprom(struct net_device *net, struct ethtool_eeprom *eeprom, u8 *data)
 {
 	struct usbnet *dev = netdev_priv(net);
-	u16 *eeprom_buff;
-	int first_word, last_word;
-	int i, ret;
+	struct ax88179_data *ax179_data;
+	int first, last, i, ret;
+	u8 *eeprom_buff;
+
+	ax179_data = dev->driver_priv;
 
 	if (eeprom->len == 0)
 		return -EINVAL;
 
 	eeprom->magic = AX88179_EEPROM_MAGIC;
 
-	first_word = eeprom->offset >> 1;
-	last_word = (eeprom->offset + eeprom->len - 1) >> 1;
-	eeprom_buff = kmalloc_array(last_word - first_word + 1, sizeof(u16),
-				    GFP_KERNEL);
+	first = eeprom->offset / ax179_data->eeprom_block;
+	last = (eeprom->offset + eeprom->len - 1) / ax179_data->eeprom_block;
+
+	eeprom_buff = kzalloc((last - first + 1) * ax179_data->eeprom_block, GFP_KERNEL);
 	if (!eeprom_buff)
 		return -ENOMEM;
 
-	/* ax88179/178A returns 2 bytes from eeprom on read */
-	for (i = first_word; i <= last_word; i++) {
-		ret = __ax88179_read_cmd(dev, AX_ACCESS_EEPROM, i, 1, 2,
-					 &eeprom_buff[i - first_word]);
-		if (ret < 0) {
+	for (i = first; i <= last; i++) {
+		u16 value, idx;
+
+		ax88179_eeprom_access_params(ax179_data, i, &value, &idx);
+		ret = __ax88179_read_cmd(dev, ax179_data->eeprom_read_cmd,
+					 value, idx, ax179_data->eeprom_block,
+					 eeprom_buff + (i - first) * ax179_data->eeprom_block);
+
+		if (ret != ax179_data->eeprom_block) {
 			kfree(eeprom_buff);
 			return -EIO;
 		}
 	}
 
-	memcpy(data, (u8 *)eeprom_buff + (eeprom->offset & 1), eeprom->len);
+	memcpy(data, eeprom_buff + eeprom->offset % ax179_data->eeprom_block, eeprom->len);
 	kfree(eeprom_buff);
 	return 0;
 }
@@ -247,12 +272,17 @@ int ax88179_get_eeprom(struct net_device *net, struct ethtool_eeprom *eeprom, u8
 int ax88179_set_eeprom(struct net_device *net, struct ethtool_eeprom *eeprom, u8 *data)
 {
 	struct usbnet *dev = netdev_priv(net);
+	struct ax88179_data *ax179_data;
 	u16 *eeprom_buff;
 	int first_word;
 	int last_word;
 	int ret;
 	int i;
 
+	ax179_data = dev->driver_priv;
+	if (ax179_data->chip_version >= AX_VERSION_AX88179A)
+		return -EOPNOTSUPP;
+
 	netdev_dbg(net, "write EEPROM len %d, offset %d, magic 0x%x\n",
 		   eeprom->len, eeprom->offset, eeprom->magic);
 

-- 
2.47.3

```